"An evidence-based approach to this complex matter is sorely needed now," he said.

"We hope that this difficult process will give Google pause for thought about how it conducts itself. Perhaps in future the company will rely less on PR spin and more on good governance and reliable product oversight," he added.

Google said that it is co-operating fully with all investigations and has apologised for the error.

In a blog post it said that it was "quite simply a mistake."

"The engineering team at Google works hard to earn your trust, and we are acutely aware that we failed badly here," the blog read.